The present invention relates to a vane wheel laying out device for sheet-by-sheet laying out of printing products for a high speed roller rotary printing press. More particularly it relates to a vane wheel laying out device for sheet-by-sheet laying out of printing products supplied from a roller rotary printing press to an associated folding apparatus.
Vane wheel laying out devices of this type are known in the art. In known vane wheel laying out devices for sheet-by-sheet laying out of printing products, the printing products fall with a relatively high speed into the vane wheel, they are then abruptly braked, and finally thrown onto the conveyor located under the vane wheel. This not uniform movement course is attributed to the known vane wheel with a wheel hub and vanes on it, and thereby to occurring non-uniform curvature course of the vane profile. As a result of these irregular speed changes, the considerable position deviations of the printing products in the sheet-by-sheet stream toward the conveyor occur.
Furthermore, unstable printing products are subjected to bending and buckling in an unacceptable manner so that the curled corners can be formed. The position and shaped deviation of the printing products in the sheet-by-sheet stream can lead to accumulation of the stream and to clogging in subsequent working stations, for example in a stacker.
One solution is disclosed in the German document DE-PS No. 15 61 054. It includes a special rotatable cylinder with withdrawable puncturing needles for a front edge of the printing product, and a roller which rotates in an opposite direction and rises through the gap in the cylinder casing from the cylinder casing surface for the rear edge of the printing product, so that in cooperation with a rotatable strip the speed of the printing product is slowed and the printing product is stretched. This solution is characterized by considerable expenses for the drive of the roller supported by the cylinder as well as for the drive control of the puncturing needles.
Another solution is proposed in the German document DE-PS No. 25 41 502. Here the speed of the printing product is reduced by the cooperation of a rotatable roller with a roller which supports a strip, so that the roller and the strip engage the printing product in the region of the rear edge. The expenses for this solution are also significant.
A special disadvantage of the proposed solutions is that they cannot produce a sensitive action on the braking force of the printing product. An adjustment of the braking action to the initial speed of the printing product which is dependent on the machine speed during leaving the band conveyor, or to its kinetic energy during falling into the vane wheel, is not possible.
In accordance with a further solution proposed for example in the German document DE-PS No. 35 15 328 C2, it is additionally found that more or less deformed printing product can be positioned in a proper position onto the conveyor. This solution is however very expensive and in the event of a multiple stream of laying out with several sheet-by-sheet streams flowing in a small distance parallel to one another, it cannot be implemented because of the space requirements.